FATE AND TRANSPORT OF NON-STEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDS) IN SOILS RECEIVING LAND APPLIED ALKALINE TREATED BIOSOLIDS IN NOVA SCOTIA

Abstract

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used to treat and prevent illness. Land application of biosolids is one potential source of NSAIDs into agricultural soils and enter as mixtures into the environment. Interactions between NSAIDs and biosolids can affect the physico-chemical characteristics of soil impacting the fate and transport of NSAIDs in the environment. A soil incubation study was conducted to measure the biodegradation rates and half-lives of individual and mixtures of naproxen (NPX), ibuprofen (IBF), and ketoprofen (KTF) with and without the addition of an alkaline treated biosolid (ATB) amendment. Results of the study showed a loss of target compounds in all treatments that was attributed to biodegradation following first-order kinetics. Soils that received the ATB amendment demonstrated inhibited dissipation of NPX in all treatments, as well as IBF and KTF in individual compound treatment over the 14-day incubation study. The dissipation of the NSAIDs in the mixture compound environment varied among the compounds. The leaching potential of NPX, IBF, and KTF was evaluated using field-based lysimeter cells receiving three rates of ATB(0, 7, and 28 Mg ha-1). All three NSAIDs in the lysimeter cells migrated vertically in the soil after spiking, but only a small amount of target NSAIDs were detected in the leachate. A mass balance analysis indicated a low accumulation of these compounds in the soil by the end of the study (Day 34) in all treatments. Application of ATB significantly increased soil pH and organic matter (OM) content but did not impact the retention of the compounds in the soil profile. Overall, all three NSAIDs were found to have low mobility in the acidic loamy sand textured soil. The fate and transport of the NSAIDs were modeled using the Root Zone Water Quality Model 2 (RZWQM2) and compared to data measured in the field-based lysimeter cells. The calibrated model adequately predicted the water seepage out of the soil profile and percent recovery of initial spiked NSAIDs in the soil at three depths and in water samples. The model performance could be further improved with more field-measured data and by considering macropore flows.